The present invention relates to a handheld power tool.
The inventive handheld power tool has a drive oscillating along a working axis and has a vibration damper. The vibration damper has a mass element suspended in a spring mechanism. The spring mechanism acts in a first direction parallel to the working axis with a first spring stiffness and it acts with a second spring stiffness in a second direction opposite the first direction. The first spring stiffness is different from the second spring stiffness.
The handheld power tool, for example, a handheld power tool having a pneumatic striking mechanism, exerts a return blow periodically on the user. The amplitude thereof may be diminished by the vibration damper, but a vibration damper having an asymmetrical design can produce a greater damping effect with the handheld power tool. The spring stiffness may have a discontinuity or a very drastic change relative to the basic position. The discontinuity leads to a highly non-harmonious movement of the mass element and non-harmonious forces, which may be more suitable for damping the machine housing.
According to one embodiment, the first spring stiffness amounts to between five and ten times the second spring stiffness. The ratio of the spring stiffness values may be used to adjust the damping of the vibration damper to the rebound behavior of the handheld power tool. The greater the ratio, the shorter and greater is the acceleration of the mass element by the stiffer side.
According to one embodiment, the mass element in the basic position is in contact with the spring. In the basic position the mass element may be arranged between two prestressed springs. According to one embodiment, the two prestressed springs are fixedly connected to the mass element. Because of the fixed connection, this results in low losses in the springs due to plastic deformation or due to friction.
According to one embodiment, the mass element is attached to a bending spring which is arranged at an inclination to the working direction. The bending spring is relaxed when the mass element is in the basic position.
The following description illustrates the invention on the basis of exemplary embodiments and figures.